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Investigation of textural quality development and post harvest softening in cox`s orange pippin apples. - FT0225

Year1 Image distribution of tissue/cell calcium in apples will be conducted. This will be used to show different degrees of firmness and will include probing the cell walls for estrified/de-estrified pectins. Commercial cox orchards will be selected for the time course study where the debvelopment of textural characteristics will be compared with the rate of fruit growth and changes in cell wall and mineral constituents during fruit development. Sites will be chosen so that a range in apple firmness at harvest can be achieved. Historical firmness data will form the frimary basis for orchard selection but proximity to a sourse of meteorological information will also be a requirement. At each site samples will be taken at weekly intervals for measuring fruit growth (weight volume and density ) and cell wall constituents (pectins and celluloses). Measurements will be made of mineral constituents in the whole fruit and in the pectin and cellulose extracts. Firmness of the cortical tissue of apples during development and storage will be measured by penetrometer and other mechanical tests and related growth patterns and changes in cell wall composition in the various orchards.Appropriate mechanical tests will be developed in conjunction with DR Julian Vincent at Reading UNiversity. HRI staff will spend time with Dr Vincent in his laboratory reviewing the mechanical testing and its affectiveness in relation to biochamical changes taking place in the cell wall and to sensory descriptions of texture. The textural characteristics of fruit from a number af additional orchards will be measured at harvest and during dtorage , and measurements of cell wall and mineral constituents carried out. Regression analysis techniques wi ll be used with a view to predicting ex-store firmness. In March 1996 there will be a review relating apple texture to physical and chemical changes in fruit during development and storage. Detailed fild experiments will be planned on the basis of year 1 results. These may be directed towards manipulation of carbohydrate production in favour of ruit and specifically cell walls or possibly towards modified nutrient uptake by developing fruits. Progress reports will be prepared at six monthly intervals . The possibility of proving practical advise to growers with the aim of precluding consignments of fruit with poor firmness potential from long-range CA storage will be considered. Year 2 Experiments will be conducted to demonstratye whether the apparent distrbution of wall bound calcium and calcium binding sites are related to tissue firmness. Work will be initiated on wall galactan distribution and galactanase activity. Detailed orchard experiments will be initiated to modify the physical properties or chemical composition of fruit at different stages of development and measure the effects of fruit firmnessat harvest and during storage . Modified textural characteristics will be related to changes in cell wall biochamistry. The validity of the original thesis will be reviewed and year 3 studies will be planned accordingly . Progress reports will be prepared at6 monthly intervals. Year 3 Whether galactan degradation in apples is linked to fruit softening during storage and whether any other wall changes are strongly correlated with tissue firmness will be determined. Studies of the relationship between fruit firmness and tissue composition for individual fruits will be initiated. The relationship between fruit firmness and fruit composition for Cox apples grown under different agronomic regimes will be confirmed and field experiments to improve fruit firmness continued. The final reports for MAFF and industrial sponsors will be prepared . The research results will be published in scientific journals where this does not contravene the IPR agrement. A written PHd thesis of the work carried out by the research assistant supervised by Drs Knox and Seymour will be submitted. A report will be produced on the practical applications of the research findings; these are likely to be measures to improve texture but also to determine 'textural potential' for different consignments of fruit and to predict the time in store to least acceptable firmness.
Time-Scale and Cost
From: 1995

To: 1999

Cost: £329,163
Contractor / Funded Organisations
Horticulture Research International, English Apples and Pears LTD
Fields of Study
Resource Efficient and Resilient Food Chain